Re: [PATCH] Add request_denied and unimplemented_packet callbacks on server side

[Andreas Schneider <asn@xxxxxxxxxxxxxx>]

On Saturday 27 February 2016 02:41:34 Nicolas Viennot wrote:
> When dealing with keepalive packets sent from the server, the clients
> reply. Having a callback on that reply allows measuring client latency.
> However, clients behave differently:
> * libssh sends an unimplemented packet reply to keepalive requests.
> * other clients like openssh sends a request denied packet to keepalive
> requests.
> These callbacks allow the server to measure the latency to the clients when
> sending keepalive requests.


Looks fine for me, Aris?


> ---
>  include/libssh/callbacks.h | 25 +++++++++++++++++++++++++
>  src/channels.c             |  5 +++++
>  src/packet.c               |  8 ++++++--
>  3 files changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/include/libssh/callbacks.h b/include/libssh/callbacks.h
> index 20c540e..22f8b08 100644
> --- a/include/libssh/callbacks.h
> +++ b/include/libssh/callbacks.h
> @@ -296,6 +296,21 @@ typedef int (*ssh_gssapi_accept_sec_ctx_callback)
> (ssh_session session,
>  typedef int (*ssh_gssapi_verify_mic_callback) (ssh_session session,
>   ssh_string mic, void *mic_buffer, size_t mic_buffer_size, void *userdata);
> 
> +/**
> + * @brief Handle a notification from the client that it received an
> unimplemented packet.
> + * @param session current session handler
> + * @param seq packet sequence number
> + * @param userdata Userdata to be passed to the callback function.
> + */
> +typedef void (*ssh_client_unimplemented_packet_callback) (ssh_session
> session, uint32_t seq, void *userdata);
> +
> +/**
> + * @brief Handle an unhandled client request denied callback.
> + * @param session current session handler
> + * @param userdata Userdata to be passed to the callback function.
> + */
> +typedef void (*ssh_client_request_denied_callback) (ssh_session
> session, void *userdata);
> +
> 
>  /**
>   * This structure can be used to implement a libssh server, with
> appropriate callbacks.
> @@ -345,6 +360,16 @@ struct ssh_server_callbacks_struct {
>    /* This function will be called when a MIC needs to be verified.
>     */
>    ssh_gssapi_verify_mic_callback gssapi_verify_mic_function;
> +
> +  /** This function will be called when the client notifies the server of
> an +   * unimplemented packet.
> +   */
> +  ssh_client_unimplemented_packet_callback
> client_unimplemented_packet_function;
> +
> +  /** This function will be called when the client notifies the server of
> an +   * non handled deny of request.
> +   */
> +  ssh_client_request_denied_callback client_request_denied_function;
>  };
>  typedef struct ssh_server_callbacks_struct *ssh_server_callbacks;
> 
> diff --git a/src/channels.c b/src/channels.c
> index ffcb1d5..6a179f9 100644
> --- a/src/channels.c
> +++ b/src/channels.c
> @@ -2039,6 +2039,11 @@ SSH_PACKET_CALLBACK(ssh_request_denied){
>    if(session->global_req_state != SSH_CHANNEL_REQ_STATE_PENDING){
>      SSH_LOG(SSH_LOG_RARE, "SSH_REQUEST_DENIED received in incorrect state
> %d", session->global_req_state);
> +
> +    if (ssh_callbacks_exists(session->server_callbacks,
> client_request_denied_function)){
> +      session->server_callbacks->client_request_denied_function(
> +        session, session->server_callbacks->userdata);
> +    }
>    } else {
>      session->global_req_state=SSH_CHANNEL_REQ_STATE_DENIED;
>    }
> diff --git a/src/packet.c b/src/packet.c
> index 7d6957c..7b98811 100644
> --- a/src/packet.c
> +++ b/src/packet.c
> @@ -464,8 +464,7 @@ SSH_PACKET_CALLBACK(ssh_packet_unimplemented){
>      uint32_t seq;
>      int rc;
> 
> -    (void)session; /* unused */
> -    (void)type;
> +    (void)type; /* unused */
>      (void)user;
> 
>      rc = ssh_buffer_unpack(packet, "d", &seq);
> @@ -477,6 +476,11 @@ SSH_PACKET_CALLBACK(ssh_packet_unimplemented){
>      SSH_LOG(SSH_LOG_RARE,
>              "Received SSH_MSG_UNIMPLEMENTED (sequence number %d)",seq);
> 
> +    if (ssh_callbacks_exists(session->server_callbacks,
> client_unimplemented_packet_function)){
> +      session->server_callbacks->client_unimplemented_packet_function(
> +        session, seq, session->server_callbacks->userdata);
> +    }
> +
>      return SSH_PACKET_USED;
>  }

-- 
Andreas Schneider                   GPG-ID: CC014E3D
www.cryptomilk.org                asn@xxxxxxxxxxxxxx